Optical ranging systems can include an illumination module and an array of 3D pixels. For example, an optical ranging system can be implemented as a time-of-flight-based system. Accordingly, an illumination module in such a system can be operable to generate modulated light. The modulated light can be incident on a scene including one or more objects. Some of the modulated light directed onto the object or objects can be reflected back to an array of demodulation pixels. In such instances, a comparison of the phase of the light first generated by (emitted from) the illumination module and the phase of the light reflected back from an object to the array of demodulation pixels can be used to determine the distance to the object.